﻿/************************************************************************

   Extended Silverlight Toolkit

   Copyright (C) 2010-2012 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://extendedsilverlight.codeplex.com/license

   Please purchase a commercial version of this toolkit if you are using
   it in a commercial product. The commercial versions support the project,
   and also include more features for each control, priority support,
   source code, updates, removed watermark, and a proprietary license.

   Visit http://xceed.com and follow @datagrid on Twitter.

  **********************************************************************/

using System;
using System.Windows.Controls;

namespace Xceed.Silverlight.ListBox
{
  internal class MoveEndOrHomeNavigationAction : PanelNavigationActionBase
  {
    #region Constructor

    internal MoveEndOrHomeNavigationAction( PanelBase panel, NavigationInfo navigationInfo )
      : base( panel, navigationInfo )
    {
    }

    #endregion

    internal override double CalculateTargetScrollIndex()
    {
      if( !this.NavigationInfo.IsForwardScrolling )
        return 0d;

      PanelBase panel = this.Panel;
      double viewportSize;
      double extentSize;

      if( panel.GetScrollingOrientation() == Orientation.Vertical )
      {
        viewportSize = panel.ViewportHeight;
        extentSize = panel.ExtentHeight;
      }
      else
      {
        viewportSize = panel.ViewportWidth;
        extentSize = panel.ExtentWidth;
      }

      return Math.Max( 0d, extentSize - viewportSize );
    }
  }
}
